Television tube coating apparatus



Dec. 19, 1967 w. H. KRAUS 3,35

TELEVISION TUBE COATING APPARATUS Filed Dec. 27, 1966 3 Sheets-Sheet l FIGI If MACH/IVE l.-

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INVENTO R WILBUR H, KRAUS ATTORNEYS Dec. 19, 1967 w. H. KRAUS 3,358,807

TELEVISION TUBE COATING APPARATUS Filed Dec. 27, 1966 5 Sheets-Shee t z INVENTOR WILBUR H. KRAUS ATTORNEYS Dec. 19, 1967 w. H. KRAUS 3,358,807

TELEVISION TUBE COATING APPARATUS Filed Dec. 27, 1966 3 Sheets-Sheet 3 FIGB FIG-7 SPIN A X15 4 7 III TILT AX/S; JMA, all:

:-Illlll INVENTOR WILBUR H. KRAUS BY Q I ,@'M

- ATToRNars United States Patent 3,358,807 TELEVISION TUBE COATING APPARATUS Wilbur H. Kraus, Birmingham, Mich., assignor to Engineering Industries, Inc., Detroit, Mi a corporation of Michigan Filed Dec. 27, 1966, Ser. No. 604,935 4 Claims. (Cl. 198-19) This invention relates to multiple station conveyor type apparatus, and more particularly to a machine for applying a photosensitive slurry to the inside front face of a television picture tube.

The television picture tube is a form of cathode ray tube having an electron gun which projects a beam of electrons along the axis of an evacuated glass envelope. The beam is deflected and focused as it passes through a series of magnetic fields, so that it impinges in a predetermined pattern on a fluorescent screen at the end of the tube. The fluorescent screen is covered with a coating of chemicals which emit visible light when struck by the stream of electrons. The color of the light is dependent upon the particular chemical used. In the case of a color television picture tube, a series of chemically distinct coatings or layers must be sequentially applied. Each chemical coating is applied in slurry form, and must be evenly distributed to a carefully controlled predetermined thickness over the entire inside face of the tube.

In order to meet the present high demand for color television sets, it becomes necessary to provide an efficient and rapid process for applying these coatings to the picture tube front face. In practice, this stage of the manufacture of color television sets has been found to be the bottleneck which slows and limits the rate of production.

The application of the slurry has been accomplished in the past by placing a TV screen on a fixture which is capable of supporting the screen while it simultaneously spins and tilts at various speeds and angles as the fixture travels past various work stations along the conveyor. Such a machine requires extremely complex controls, and in the event of a malfunction of any of the fixtures, the whole machine is rendered inoperable. Such a breakdown is intolerable in a process requiring such a high rate of production.

Accordingly, it is an object of this invention to provide an improved multiple station conveyor type apparatus for applying a fluorescent coating to a television screen.

It is a further object of this invention to provide an improved fixture for firmly and safely supporting a glass TV screen while it simultaneously spins and tilts through predetermined angles during the process of coating the screen with a fluorescent slurry.

It is still another object of this invention to provide an improved television screen supporting fixture equipped with reliable and greatly simplified controls for providing the desired predetermined angles of tilt and speeds of rotation in a predetermined sequence as the fixture travels past various processing stages during the application of the photosensitive coating.

It is another object of this invention to provide an improved fixture for supporting a television screen during the application of a photosensitive slurry, which fixture can be rapidly removed from the conveyor in the event of a malfunction, and which has interchangeable controls.

These and other objects of this invention will become apparent from the following specification when considered in conjunction with the accompanying drawings.

In these drawings:

FIG. 1 is a plan view of a single fixture of the conveyor apparatus, showing a portion of adjacent fixtures in phantom.

FIG. 2 is a schematic diagram of the control for the fixture.

FIG. 3 is a side elevational view in the direction of arrows 33 of FIG. 1.

FIG. 4 is an enlarged side elevational view of the structure for securing the fixture to the conveyor chain.

FIG. 5 is a rear view of the structure of FIG. 4.

FIG. 6 is an enlarged plan view of a portion of the TV screen supporting fixture.

FIG. 7 is a front cross-sectional elevation of the fixture substantially in the direction of :arrows 77 of FIG. 6.

Referring now to FIGS. 1 and 3 of the drawings in particular, the machine comprises a plurality of identical fixtures 10 which are carried along a conveyor. In practice, such machines have been designed in a race track plan view configuration and of a size large enough to accommodate sixty such fixtures. The fixtures are spaced quite close to each other, as can be seen from FIG. 1. As the fixtures travel along with the conveyor, they pass a series of stations at which various operations are automatically performed, as will be described hereinafter. Each fixture 10 generally comprises a workpiece supporting table 12 mounted on a tiltable housing 14. Housing 14 is pivotally mounted on fixture platform 16 and is capable of tilting or pivoting about an axis parallel with the center line of the machine.

Also rigidly secured to fixture platform 16 is a tilt drive motor 18 and a spin drive motor 20. The controls for the fixture are contained within control cabinet 22, to be further described below.

Each fixture 10 is supported on an upper and lower horizontal rail 24, 26 respectively, forming a part of the stationary conveyor apparatus. A plurality of guide rollers 28 are rotatably mounted on the fixture platform 16 and engage rails 24 and 26 to maintain the fixture in proper alignment with the machine as it moves along with the conveyor. Each fixture is removably secured to the conveyor drive chain 30 in a manner to be described below. Chain '30 is operatively connected through appropriate sprockets and shafts to a conveyor drive motor (not illustrated).

To trigger the fixture controls at predetermined points or stations along the machine, a bank of limit switches 32 is fixed to the back portion of fixture platform 16. These limit switches are so positioned as to come into registry with one of a group of identical banks of earns 34 positioned at appropriate stations along the machine. In practice, machines have been manufactured with nineteen pairs of limit switches and cooperating cams. Five provide a range of rates of tilting movement; two control the direction of tilting movement; five control the desired angle of tilt; one tilt reset; another five to provide a range of spin speeds; and a spin reset. These limit switches are electrically connected to appropriate circuits in control cabinet 22. The particular circuitry employed does not form a part of the invention, and hence is not illustrated.

Electrical power for the fixture controls is supplied by means of a pair of trolley ducts 36 fixed to the frame of the machine and in which ride a pair of shoes 38 carried by the fixture and connected to appropriate circuitry thereon.

The tilt mechanism is illustrated in detail in FIGS. 6 and 7 of the drawings. Connected to the tilt drive motor 18 is an angle drive 40 having a pinion gear 42 secured to output shaft 44. Pinion 42 is in meshing engagement with sector 46 secured to the tilt axis shaft 48. The tiltable housing 14 is pivotally supported by arms of the fixture platform 16, as illustrated in the plan view of FIG. 1.

The spin drive mechanism is also best illustrated in FIGS. 6 and 7. An angle drive unit 50 is connected to spin drive motor 20 and has an output shaft 52 provided with a beveled pinion gear 54. Pinion 54 meshes with a second bevel gear 56 within tiltable housing 14. Bevel gear 56 is fixed for rotation with sleeve shaft 58, which in turn causes the workpiece table 12 to rotate.

It can be seen that operation of tilt drive motor 18 causes sector 46 to rotate, carrying with it housing 14. This mechanism thus produces a tilting or inclining of TV screen supporting table 12. Simultaneously, table 12 may be spun by spin drive motor 20, since the spin drive train is unaffected by the angle of tilt of housing 14 and table 12.

Rigidly mounted on fixture platform 16 is angle sensor housing 60. Within this housing is mounted a series of limit switches 62 (see FIG. 7) which are selectively engaged by a series of cams 64 mounted for rotation with tilt shaft 48. This unit functions to signal the control circuitry when predetermined angles of tilt have been established.

Referring now to the details of the workpiece supporting table 12, illustrated in FIGS. 6 and 7, three pairs of L-shaped clamps 66 are mounted for sliding movement in a series of three clamp bases 68 spaced at 120 degree intervals around the table. At the upper inner face of each of clamps 66 is a pad 7 fabricated of a soft material so as to avoid marring the glass TV screen '72. Clamps 66 are controlled by a series of connecting links 74 pivotally connected to the upper end of control shaft 76. The action of the clamps is controlled by a handle 73 at the lower end of control shaft 76. A series of springs 80 functions to bias clamps 66 toward the center of the table in a clamping position. Additionally, three supporting pads 82 are provided to support and stabilize TV screen 72.

Referring now to FIGS. 3 through 5, fixture 10 is removably connected to conveyor drive chain 30 in the following manner. Spaced along chain 30 at intervals is a chain link having a pair of L-shaped arms 84 extending toward the fixture. Arms 84 are adapated to be inserted into a slot 86 in the rear portion of fixture platform 16. The upper portion of slot 86 is covered by a retaining plate 88 which is secured to the fixture platform by a pair of bolts 90. A third bolt 92 passes through the lower of the two arms 84 into the fixture platform to complete the assembly.

To drivingly connect the fixture to conveyor chain 30, bolts 96 are loosened slightly and the fixture is lifted into a position such that slot 86 is above upper arm 84 of an appropriate chain link. The fixture may then be lowered into place and bolts 90 and 92 secured in place. With shoes 38 riding in trolley ducts 36, the fixture is drivingly and electrically ready to operate with the conveyor.

In operation, the glass TV screen is loaded onto the fixture 10 in an open end up configuration as illustrated in FIG. 7. Clamping control handle '78 is then rotated to firmly clamp the TV screen to supporting table 12. The screen is then ready to proceed along the conveyor for processing.

The first station on the machine is a cleaning station, where dirt or film is removed from the glass TV screen. At this station it is necessary that the TV screen be inverted so that the open end is down. This requires that the tiltable housing tilt or pivot through 180 degrees. This movement is accomplished in the following fashion. At this station, three of the cams in cam bank 34 would actuate corresponding limit switches in limit switch bank 32. One limit switch would signal the tilt motor to operate in a direction to tilt table 12 downward. A second switch would direct the tilt motor to provide 180 degrees of tilt movement, and the third switch would signal a rate of angular tilting movement. No other switches would be actuated.

As fixture 10 passes through this cleaning station, then the workpiece supporting table 12 commences to pivot or tilt downwardly through 180 degrees. During this process, streams of cleaning fluid are directed upwardly at the inside face of TV screen 72 to wash any dirt or film from the screen.

Since the fixture controls are wired to initiate and maintain a particular action once triggered until subsequently cancelled, the reset switches (one for tilt and one for spin speed) are automatically tripped by appropriately placed cams when it is desired to terminate or change a control signal.

Each of the seven pairs of cams and limit switches in angle sensor housing 69 functions to signal tilt motor 18 when the particular desired angle of tilt has been reached. It is necessary that these switches 62 function in combination with the five tilt angle controlling switches of switch bank 32, otherwise the tilt motor would shut off when the first of switches 62 to be reached was tripped.

Following the cleaning operation, the fixture arrives at a drying station where blasts of drying hot air are applied to the TV screen. No change of tilt angle occurs here, and the table is still non-rotating.

Following the cleaning and drying stations, the fixture reaches the slurry dispensing station. At this station it is necessary that the TV screen be oriented in an open end up configuration, and that it remain in a non-rotating condition. Therefore, three limit switches are tripped to signal the appropriate direction, angle, and rate of tilt to return the screen to this position.

As a measured quantity of the slurry is dispensed into the inverted bowl of the TV screen, the screen starts to rotate very slowly, and tilts slightly. The combination of the rotating and tilting functions to spread the slurry over the entire inner face of the screen. Accordingly, switches to signal direction, angle and rate of tilt as well as spin speed are triggered.

After distribution of the slurry is substantially complete, the screen stops rotating and tilts to an angle of degrees so as to dump any excess slurry from the screen. Appropriate limit switches would be actuated as the fixture reached the dumping station. Then the screen starts to spin at a high speed to maintain the desired thickness and distribution of the slurry as the screen passes into a drying stage to fix and harden the slurry. When this stage has been completed, the screen is turned degrees to the downward attitude to be unloaded from the fixture.

The entire sequence described above occurs on one side of the race track-shaped machine. The TV screen is unloaded and taken to a separate facility where the hardened coating is exposed to complete the photosensitizing process. Then the TV screen is returned to the race track and loaded onto the opposite side of the machine, where the coating process is repeated with a chemically different slurry composition. This second coating will then be exposed and rendered photosensitive in a different color. The process is repeated on the first side of a second machine with a third distinct coating, and after exposure the screen is returned to the second side of the second machine where a non-photosensitive covering coating is applied. The process is then complete.

The machine described above provides a highly efiicient and simplified technique for accomplishing the intricate process of coating glass TV screens. Each of the identical fixtures carries its own identical controls in a readily removable control cabinet. If a malfunction arises in the controls, the cabinet can be quickly and easily pulled off the fixture, or the whole fixture removed from the conveyor if necessary, and replaced with a spare. In contrast, were the controls mounted on the stationary machine itself, a malfunction would require the whole machine to be inactivated until repaired. In the present invention, only a series of cams is mounted on the stationary portion of the machine.

Another advantage of this unique machine is in the construction of the TV screen retaining clamps, which provide safe and sturdy retention for the heavy glass screen while it is tilting and spinning at speeds up to 150 rpm. Yet only a single control wheel is required to clamp or release the screen from the table.

This invention may be further developed Within the scope of the following claims. Accordingly, the above specification is to be interpreted as illustrative of only a single operative embodiment, rather than in a strictly limited sense.

I now claim:

1. In a multiple station conveyor type apparatus having a stationary supporting frame, a power operated conveyor, a plurality of identical workpiece supporting fixtures removably secured to the conveyor for movement therewith through the various stations, the improved fixture and fixture control system that comprises:

a platform removably secured to the conveyor for movement therewith;

a tiltable housing pivotally secured to said platform for pivotal movement in relation thereto about a tilt axis passing through said housing;

tilt drive means secured to said platform and drivingly connected to said tiltable housing for causing said tiltable housing to rotate about the tilt axis;

workpiece gripping means for releasably supporting and gripping a workpiece, said workpiece gripping means being rotatably mounted on and with respect to said tiltable housing about a spin axis perpendicular to said tilt axis and passing through a workpiece secured within said gripping means;

spin drive means secured to said platform and connected to said workpiece gripping means for causing said workpiece gripping means to spin about said spin axis;

control means for controlling the operation of said tilt drive means and said spin drive means in timed relation to the position of the fixture relative to the conveyor stations comprising a set of triggering devices located at each of a plurality of stations along the conveyor and mounted on the conveyor supporting frame, a set of trigger responsive devices secured to said fixture platform and so positioned as to operatively register with said triggering devices as the fixture passes said triggering stations, tilt angle sensing means connected to said platform and to said tiltable housing for sensing the angle of tilt of said housing, and electrical circuit means secured to said fixture platform and connected with said trigger responsive means, said tilt angle sensing means, and with said spin drive means and said tilt drive means.

2. The apparatus of claim 1, wherein the workpiece is a concave glass television picture tube screen and wherein said workpiece gripping means comprises a base perpendicular to said spin axis, a plurality of workpiece engaging pads spaced around said spin axis and mounted for reciprocating movement on said base along axes substantially radial with respect to said spin axis, a pad control shaft concentric with said spin axis, pad control links interconnecting said pad control shaft and said pads, and a handle on the end of said control shaft, whereby simultaneous movement of said pads can be effected by said handle for clamping or releasing said workpiece on said fixture.

3. The apparatus of claim 1, wherein said spin drive means further comprises a first bevel gear rotatably mounted within said tiltable housing and coaxial with said tilt axis, a second bevel gear meshed with said first bevel gear and rotatably mounted within said tiltable housing and coaxial with said spin axis and fixed to said workpiece gripping means base, and wherein said pad control shaft is disposed coaxially with and inside said second bevel gear and workpiece gripping means base.

4. The apparatus of claim 1, wherein the power operated conveyor includes a driving chain, and wherein said chain is provided with arms rigidly connected thereto at spaced intervals along its length, said fixture platform being provided with a slot to receive said chain arms and securing means to lock said arms in said slot, whereby said fixture may be readily drivingly connected to said chain merely by securing said chain arm in said platform slot.

References Cited UNITED STATES PATENTS 2,770,557 11/1956 Atti 118503 X 3,319,556 5/1967 Fiore 198l9 X 3,319,759 5/1967 Hajduk et a1. 198-19 EVON C. BLUNK, Primary Examiner. M. L. AJEMAN, Assistant Examiner. 

1. IN A MULTIPLE STATION CONVEYOR TYPE APPARATUS HAVING A STATIONARY SUPPORTING FRAME, A POWER OPERATED CONVEYOR, A PLURALITY OF IDENTICAL WORKPIECE SUPPORTING FIXTURES REMOVABLY SECURED TO THE CONVEYOR FOR MOVEMENT THEREWITH THROUGH THE VARIOUS STATIONS, THE IMPROVED FIXTURE AND FIXTURE CONTROL SYSTEM THAT COMPRISES: A PLATFORM REMOVABLY SECURED TO THE CONVEYOR FOR MOVEMENT THEREWITH; A TILTABLE HOUSING PIVOTALLY SECURED TO SAID PLATFORM FOR PIVOTAL MOVEMENT IN RELATION THERETO ABOUT A TILT AXIS PASSING THROUGH SAID HOUSING; TILT DRIVE MEANS SECURED TO SAID PLATFORM AND DRIVINGLY CONNECTED TO SAID TILTABLE HOUSING FOR CAUSING SAID TILTABLE HOUSING TO ROTATE ABOUT THE TILT AXIS; WORKPIECE GRIPPING MEANS FOR RELEASABLY SUPPORTING AND GRIPPING A WORKPIECE, SAID WORKPIECE GRIPPING MEANS BEING ROTATABLY MOUNTED ON AND WITH RESPECT TO SAID TILTABLE HOUSING ABOUT A SPIN AXIS PERPENDICULAR TO SAID TILT AXIS AND PASSING THROUGH A WORKPIECE SECURED WITHIN SAID GRIPPING MEANS; SPIN DRIVE MEANS SECURED TO SAID PLATFORM AND CONNECTED TO SAID WORKPIECE GRIPPING MEANS FOR CAUSING SAID WORKPIECE GRIPPING MEANS TO SPIN ABOUT SAID SPIN AXIS; CONTROL MEANS FOR CONTROLLING THE OPERATION OF SAID TILT DRIVE MEANS AND SAID SPIN DRIVE MEANS IN TIMED RELATION TO THE POSITION OF THE FIXTURE RELATIVE TO THE CONVEYOR STATIONS COMPRISING A SET OF TRIGGERING DEVICES LOCATED AT EACH OF A PLURALITY OF STATIONS ALONG THE CONVEYOR AND MOUNTED ON THE CONVEYOR SUPPORTING FRAME, A SET OF TRIGGER RESPONSIVE DEVICES SECURED TO SAID FIXTURE PLATFORM AND SO POSITIONED AS TO OPERATIVELY REGISTER WITH SAID TRIGGERING DEVICES AS THE FIXTURE PASSES SAID TRIGGERING STATIONS, TILT ANGLE SENSING MEANS CONNECTED TO SAID PLATFORM AND TO SAID TILTABLE HOUSING FOR SENSING THE ANGLE OF TILT OF SAID HOUSING, AND ELECTRICAL CIRCUIT MEANS SECURED TO SAID FIXTURE PLATFORM AND CONNECTED WITH SAID TRIGGER RESPONSIVE MEANS, SAID TILT ANGLE SENSING MEANS, AND WITH SAID SPIN DRIVE MEANS AND SAID TILT DRIVE MEANS. 